The next term is double the previous term, so that the
-th term is given recursively by

This rule tells us that



and so on, with the explicit rule

for
.
If 512 is the
-th term in the sequence, then

<span>25.7 years
The rule of 72 is a simple approximation on how long it will take to double your money. You simply divide 72 by the interest rate and you'll have your estimate on the number of years it will take. So
72 / 2.8 = 25.7 years.
To demonstrate that it's just an estimate, you can take the log of 2 and divide by the log of 1.028 to get the exact value. This far more complicated calculation gives the result of 25.1 years. And to be honest, the estimate of 25.7 years is more than close enough for such an quick and easy rule of thumb.</span>
Forts then you take the 1-6 to get the money back and get your credit
Answer:

Step-by-step explanation:
we have

Solve for a
That means ----> Isolate the variable a
Factor 3 in the numerator right side

Simplify right side

subtract a both sides


subtract 1 both sides


Rewrite
